code: def test_memo(self):
      self.assertIs(sentinel("a"), sentinel("a"))
  
file_path: catalyst/tests/utils/test_sentinel.py
imports: from copy import copy, deepcopy
  from pickle import loads, dumps
  from unittest import TestCase
  from weakref import ref
  from catalyst.utils.sentinel import sentinel
label_desc: Use image node_id 5 for calling the SentinelTestCase obj's underlying member method code with example usage: obj.test_memo() without return types